Rotary compressor



,1966 M. w. GARLAND ETAL 3,

ROTARY COMPRESSOR Original Filed June 6. 1963 s Sheets-Sheet 1 FIG. 1

(I m INVENTOR M. w. GARLAND 1/ M. Y. 'DREKSLER I1 BY ATTORNEY Dec. 13, 1966 M. w. GARLAND ETAL 3,291,384

ROTARY GOMPRE S SOR 6 Sheets-Sheet 2 Original Filed June 6. 1963 INVENTOR M. W. GARLAN D Dec. 13, 1966 M. w. GARLAND ETAL 3,291,384

ROTARY COMPRESSOR 6 Sheets-Sheet 5 Original Filed June 6, 1963 FIG. 4

FIG.

INVENTOR M. W. GARLAND M Y. DREKSLER 1966 M. w. GARLAND ETAL 3,

ROTARY COMPRESSOR Original Filed June 6, 1963 6 Sheets-Sheet 4 INVENTOR M. W. GARLAND M. Y. DREKSLER Dec. 13, 1966 M. w. GARLAND ETAL 3,291,384

ROTARY COMPRES S OH 6 Sheets-Sheet 5 Original Filed June 6, 1965 INVENTOR M. W. GARLAND M. Y. DREKSLER ATTORNEY Dec. 13, 1966 M. w. GARLAND ETAL 3,291,384

ROTARY COMPRES SOR OriginalFiled June 6. 1963 6 Sheets-Sheet 6 I INVENTOR M. W. GARLAND M. Y. DREKSLER (,1 ATTORNEY United States Patent 3,291,384 ROTARY COMPRESSOR Miiton W. Garland and Moshe Y. Dreksler, both of Waynesboro, Pa, assignors to Frisk Company, Waynesboro, Pa., a corporation of Pennsylvania Continuation of application Ser. No. 286,037, June 6, 1963. This application Sept. 15, 1965, Ser. No. 487,443 Claims. (Cl. 230-152) This application is a continuation of application Serial No. 286,037, filed June 6, 1963, now abandoned. This invention relates to vapors and gases and to apparatus and equipment for altering the density and temperature of such vapor and gases.

The invention relates particularly to a rotary sliding vane compressor unit which pumps and compresses the gases of a refrigeration system and which is of maximum eificiency while maintaining a minimum noise level.

Rotary sliding vane compressors generally include a cylinder, a body or rotor eccentrically mounted within the cylinder, and a plurality of vanes extending from such rotor in contact with the cylinder walls. Due to the eccentric mounting of the rotor the vanes slide in and out of grooves in the rotor and define spaces or pockets between such vanes which vary in volume as the rotor rotates. Hence, by introducing a compressible refrigerant gas between a pair of such blades at a position where the volume is relatively large and discharging such gas at a position where the volume is relatively small, compression is effected.

Due to the continuous friction created by the sliding vanes it is necessary to constantly introduce and remove a lubricant in order to maintain friction at a minimum and prevent the attainment of temperatures which injure the compressor elements or the lubricant and which eventually will interfere with the operation of the apparatus.

Heretofore rotary vane compressors, which were primarily designed for compressing a fluid such as air in an air conditioning system, have been utilized in a refrigeration sys em and since the compression ratio and the efficiency of operation have not been as critical in an air conditioning system these compressors have proved inefficient, noisy, difficult to maintain, have not produced the desired compression ratio, and for other reasons have not been satisfactory, In compressors designed specifically for a refrigeration system, the horsepower requirements have been excessive in comparison to the input-output ratio and the noise has been of sufficient intensity to prevent their use in many applications.

Accordingly, it is a primary object of the invention to provide a rotary sliding vane compressor adapted to operate at maximum efficiency under normal conditions and with a minimum of noise and resulting wear.

Another object of the invention is the provision of a rotary sliding vane compressor having ports arranged for maximum efficiency, safety of operation and a minimum of noise under a wide range of operating conditions.

A further object of the invention is to provide a rotary compressor unit including a coolant separator for separat ing the compressed gas from the lubricant and with a lubricant heat exchanger for cooling the lubricant.

A still further object of the invention is to provide a rotary sliding vane compressor in which the sliding vanes assist in the compression of the refrigerant.

Other objects and advantages of the invention will be apparent from the following description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a vertical section through the axis of the rotor of the compressor unit;

FIG. 2, a section taken along the line 2-2 of FIG. 1;

FIG. 3, an enlarged fragementary perspective of one of the vanes and illustrating the porting thereof;

Patented Dec. 13, 1966 FIG. 4, an enlarged fragmentary side elevation of one side of the rotary compressor illustrating the inlet ports;

FIG. 5, an enlarged fragmentary side elevation of the opposite side of the compressor illustrating the discharge ports;

FIG. 6, a perspective of a complete rotary compressor unit;

FIG. 7, a fragmentary section of the compressor cylinder illustrating the suction and discharge ports;

FIG. 8, an enlarged fragmentary detail section taken along the line 8-8 of FIG. 1;

FIG. 9, an enlarged fragmentary detail section taken along the line 99 of FIG. 7;

FIG. 10, an enlarged top plan view of the oil separator;

FIG. 11, a side elevation of the oil separator with portions broken away for clarity;

FIG. 12, a vertical section taken along the line 1212 of FIG. 11;

FIG. 13, an enlarged fragmentary section taken along the line 13-13 of FIG. 11;

FIG. 14, a section taken along the line 1414 of FIG. 13;

FIG. 15, an enlarged top plan view of the lubricant heat exchanger;

FIG. 16, a side elevation of the structure of FIG. 15; and

FIG. 17, an enlarged fragmentary vertical section taken along the line 17-17 of FIG. 15.

Briefly stated the present invention is a rotary sliding vane compressor unit which uses an excess of lubricant for removing heat of compression and for the sealing of structural clearances when utilized for compressing gases in a refrigerant vapor pumping and compressing system and includes a compressor having a cylindrical cavity and a rotor having multiple sliding vanes eccentrically mounted within said cavity. A plurality of inlet and discharge ports are located in the circumferential portion of the cylinder and extend substantially along the full length of the rotor, the effective area of such ports being in direct proportion to the total nominal gas or vapor volume flowing through the pockets created by the sliding vanes and the eccentric mounting of the rotor. A lubricant is introduced under pressure into such pockets when such pockets are subtantially at their greatest volume to provide lubrication for the moving parts, to aid in the compression of the fluid being compressed and to absorb the heat of compression. After the gas is discharged from the compressor, it passes through a separator which removes the lubricant from the gas and directs such gas into the refrigerating system while returning the lubricant through a heat exchanger to remove heat of compression that has been absorbed and thereafter to be reinjected into the compressor.

With continued reference to the drawings the rotary compressor unit includes a base 10 constructed of a pair of generally parallel side members 11 rigidly connected by cross members 12 and 13. A compressor housing or cylinder 14- is mounted on the cross members 13 in any desired manner as by bolts or the like. The housing 14 is provided with a cylindrical cavity having an internal peripheral wall 15 and such housing is provided at one side with an outwardly extending wall 16 defining an inlet for gas and an outwardly extending wall 17 on the opposite side defining an outlet for such gas after it has been compressed.

The housing 14 has a plurality of angularly disposed slots or ports 18 within the area defined by the wall 16 which provide communication between the interior and the exterior of such housing through the wall 15 for the ingress of a refrigerant such as ammonia gas. Likewise the housing 14 has a plurality of angularly disposed slots or ports 19 disposed in the area confined within the wall 17 which provide for the discharge of the refrigerant from the housing 14. A rotatable body or rotor 20 is eccentrically mounted within the compressor housing 14 in such a position that the rotor 20 will be in close proximity to the wall 15, and with the lubricant, form a seal at a point of tangency adjacent to the upper extremity of the ports 19. The rotor 20 has a plurality of radial grooves 21 each of which is ada ted to slidably receive a vane 22 and each of such vanes is capable of moving radially of the grooves due to centrifugal force when the rotor 20 is rotated.

Rotation of the rotor causes the vanes 22 to move outwardly through centrifugal force and to continuously engage the inner peripheral wall of the housing 14. Due to the eccentric mounting of the rotor the vanes form spaces or pockets between such vanes which vary in volume as the rotor rotates. Each of the vanes has a plurality of recesses or grooves 23 on one side which extend from a position spaced from the outer longitudinal edge through the inner longitudinal edge. The grooves are disposed at an angle to the edges of the vanes and preferably are located in overlapping relation to prevent uneven wear on the rotor as the vanes move in and out of the grooves 21. The rotor 20 preferably is constructed of relatively dense material such as steel or the like and the vanes are constructed of laminated fiber impregnated and bonded with a resin, such as asbestos and melamine, which provides a relatively smooth surface capable of retaining a film of lubricant to reduce friction and prevent overheating and subsequent wear on the vances as they move in and out of the rotor grooves. Preferably the vanes are of a weight sutficient to overcome any tendency of the gas pressure to push the vanes back into the grooves or recesses 21.

A suction manifold 26 is connected at one end to the outwardly extending wall 16 by fasteners 27 and to the opposite side of such manifold is attached an adapter plate 28 by fasteners 29. The plate 28 is connected to one end of an inlet pipe 30 through which the refrigerant is introduced into the compressor housing from a suction trap 31. The refrigerant is introduced into the suction trap through an inlet line 32 from the refrigerating system and any impurities in the refrigerant will be filtered out by a screen (not shown) contained within such suction trap.

A discharge manifold 35 is connected by fasteners 36 to the outwardly extending wall 17 and such manifold is provided with a sump 37 for collecting any lubricant entrained in the flow of the refrigerant. A discharge valve 38 is mounted on the manifold 35 and an oil lift sleeve 35 is provided within the manifold 35 and directs the flow of gas and lubricant upwardly to an oil separator 39. The oil separator is adapted to remove any lubricant from the compressed refrigerator gas in a manner to be described later and the compressed refrigerant is then directed into the refrigerating system through a line 40 having a check valve 40' while the lubricant is discharged through a drain 41 into a reservoir 42.

In order to introduce the lubricant into the compressor housing 14 such lubricant is removed from the reservoir 42 through a line 43, having a shut-off valve 43, connected to an oil pump 44 and is forced through a lubricant heat exchanger 45, the details of which will be described later. From the heat exchanger the lubricant is passed through a filter 46 and a one-way check valve 47 into a distribution header 48 from which it is introduced into the bottom portion of the compressor housing 14 through a series of inlet ports 49 connected to the header by lines 50. The inlet ports 49 are equally spaced along the longitudinal axis of the housing for equal distribution of the lubricant throughout the housing and are spaced from the ports 18 a distance slightly greater than the spacing of the vanes so that the lubricant is introduced into the spaces or pockets between the vanes during the time that such pockets are of relatively large capacity. The lubricant is introduced into the compressor housing under pressure which is greater than the pressure of the fluid within the pocket at that time and thereby aids in the compression of such fluid. More lubricant than is actually needed for lubrication is introduced into the compressor so that the heat, created by the compressing of the gas, will be absorbed by the excess lubricant.

The rotor 20 has an axle 53 extending outwardly from one end adapted to be driven by a motor or other power plant 54 mounted on the cross members 12. An axle 55 is fixed to the opposite end of the rotor 20 and the outer or free end of such axle is drivingly connected to the oil pump 44 to circulate lubricant through the system. Each of the axles 53 and 55 has an enlarged portion 56 rotatably supported by axially slidable bearings 57 carried by bearing housings 58 mounted on each end of the housing 14 by fasteners 59. The axle 53 has a spring loaded double rotary seal 60 carried within a seal housing 61 which prevents the leakage of lubricant while permitting slight axial movement of the rotor and axles.

The ends of the rotor 20 and vanes 22 preferably are in very close proximity to the inner wall of the bearing housings 58 to reduce leakage around such vanes to a minimum. In order to correctly position such rotor and vanes, the axle 55 is provided with a thrust bearing 64, the outer race of which is confined between a flanged ring 65 and a washer 66. The washer 66 is retained within a recess in the bearing housing 58 and is maintained in position by an oil pump housing 67 mounted on the bearing housing 58 by fasteners 68. A pair of inspection ports 69 are provided in the compressor housing 14 so that the gap between the rotor and vanes and the bearing housings can be observed during the assemblyprocess. If it is determined that the rotor is bearing against one of the housings the washer 66 may be shaved to permit free rotation of the rotor, or if the washer is too thin, a conventionalshim, not shown, may be inserted. When the spacing between the rotor and the bearing housings has been established, the inspection ports 69 are closed by plugs 70. If desired, two seal ring retainers are mounted on each of the axles 53 and 55 adjacent to the rotor 20 and have seals 72 engaging a peripheral opening 73 in each of the bearing housings 58.

As illustrated in FIGS. 4, 7, and 9 a plurality of suction ports 18 of varying lengths are provided along substantially the entire effective length of the rotor and preferably are cast when the compressor housing is formed. Such slots have generally parallel walls 75 on the inner portion of the housing and tapered diverging walls 76 on the outer portion thereof to reduce turbulence. The ports 18 are arranged in angular overlapping relation in such a I manner that substantially the entire surface of the tips of the vanes are exposed to the ports to prevent localized wear on such tips which would eventually affect the sealing of the vanes against the internal wall 15. The area of the ports 18 is great enough so that the pockets between the vanes will be completely filled with the gas when the pockets are at their greatest volume.

After the vanes of the rotor have passed the seal point, the vanes again begin to move outwardly and the high pressure gas contained in the slots will expand and a reduction in pressure is created in the pockets. In order to relieve such perssure reduction, cretain of the ports 18 extend upwardly substantially to the top of the rotor to permit gas to enter the pockets and alleviate any reduction drag. As the pockets continue to enlarge due to the eccentric mounting of the rotor, additional ports are exposed in direct proportion to the volume of the pocket to permit additional gas to be introduced until such time as the pocket is diametrically opposite the seal point and is at its greatest volume. When the vanes have passed the lowermost point of the ports, the gas is sealed within the pockets and is compressed as the rotor rotates.

The discharge ports 19 are constructed in the same manner as the suction ports 18 and are in fixed relation to the position of the vanes so that the compressor has a fixed nominal compression ratio. The efficient operation Without excessive power penalty is facilitated at substantially different compression ratios due to the distribution and sizing of effective discharge porting areas. When the desired compression has been reached the gas will be exposed to certain of the discharge ports 19 (FIG. 7) to permit the compressed gas within the pockets to escape. As the rotor continues to rotate the gas within the pockets will continue to be compressed and in order to maintain the gas being discharged substantially at a nominal constant pressure, such gas will be exposed to other slots of varying lengths, the effective areas of which are in direct proportion to the volume of gas remaining within the discharging pockets as the latter moves relative to the discharge ports 19, to the extent that the velocity of the gas being discharged will be no less than 75 percent or more than 125 percent of the peripheral velocity of the vanes. This may be expresed generally by the over-simplified equation Q=VA in which Q is the quantity of gas that has been compressed and is being discharged; V is the average velocity of the tip speed of the vanes in the area of the discharge ports; and A is the total effective area of the discharge ports. The effective unrestricted gas flow area of the slots is slightly less than the total area of such loss due to turbulence effect formed around the periphery of the slots which resist such flow of gas. As an example, if one of the slots were /8 inch wide and three inches long, the total area would be .375 square inch; however, the effective area might be in the neighborhood of .325 square inch. Since the seal point between the rotor and the compressor housing is located substantially at the uppermost cut-off point of the discharge ports, all of the gas is expelled from the pocket through such ports. It is desirable that the seal point be located in this position and that the discharge slots be at their maximum capacity so that sub tantially all of the non-compressible lubricant will be discharged with a minimum change in direction of flow. When the fixed seal point between the rotor and housing is shifted in direction of rotation by more than 10 degrees measured from the uppermost cut-off point of discharge portings the noise level increases substantially.

For maximum operating efllciency and minimum overall friction losses the blade weights are proportioned for sealing at approximately one-half the maximum design r.p.m., thus enabling the use of two speed motors. The effective area of the discharge ports is somewhat less than the effective area of the suction or inlet ports because the volume of the gas has been reduced and will flow through smaller openings at the desired velocity. As an example, compressor portings designed for a three to one ratio would change an inlet volume of 200 cubic feet to a discharge volume of approximately 60 cubic feet. The velocity of the gas will fall sharply when it is discharged into the large end of the discharged manifold however, such gas will increase gradually in velocity as it moves toward the smaller discharge end and through the oil lift sleeve 35 into the discharge valve 38.

Due to the location of the seal point relative to the suction ports and the discharge ports, as well as a substantially constant rate of discharge, maximum efficiency and quietness is obtained, since there will be no fluctuation of pressure at the discharge ports and consequently no gas Waves or shock waves. The motor 54 is required to rotate the rotor only enough to reach the compression ratio whereupon substantially all of the gas is discharged and no power is required to further compress gas which would be present if the seal point were not located at the cut-off point of the discharge ports.

The reciprocating movement of the vanes assists in the compressionof the gas as well as the moving of the vanes outwardly, particularly during the initial stages of such outward movement. The reason for this is that when the pockets are being filled with gas, such gas can flow through the grooves 23 into a well created by the vanes moving out of the grooves 21, and after the pocket has reached its greatest volume and the ingress of gas has been cut off the vanes will be forced back into the grooves. Such movement will compress the gas within the well and force such gas outwardly through the recesses 23 into the pockets until such time as the recesses 23 are received within the grooves 21, whereupon the gas remaining in the well cannot escape and will be further compressed. After the vanes have passed the seal point between the rotor and the compressor housing and the pressure i relieved on the tips of the vanes, the gas which has been compressed within the well will expand and exert an outward force against the vanes to assist centrifugal force in maintaining the vanes against the peripheral wall 15 of the compressor housing until such time as the recesses are again exposed to the pockets.

With reference to FIGS. 10-14 an oil separator 39 is provided for separating the compressed gas from the lubricant. In the disclosed modification the gas and entrained lubricant mixture passes through the discharge manifold 35 and oil lift sleeve 35' of the compressor and through the discharge valve 38 into a T connection 78. The gas. and entrained lubricant mixture will travel through a pair of inlet pipes 79 until discharged into opposite ends of the oil separator 39. The oil separator includes a plurality of pairs of baffles 80- and 81 having multiple flanged openings 82 and 83, respectively. The baffles of each pair are spaced relatively close together and the flanged openings of one baffle are staggered from the flanged openings of the other baifle so that the mixture will pass through the openings 82 of the baflle 80 and impinge upon the baffle 81 in such a manner that such mixture must change direction to pass through the flanged openings 83 of such baflle.

When the mixture impinges upon the second baffle the heavier particles of lubricant will have a tendency to continue to move in the same direction by momentum and cause the particles of lubricant to strike the solid surface of the baflie 81 and cling thereto and while the gas is changing direction and flowing through the flanged opening 83 the lubricant will flow by gravity to the bottom of the separator and will drain toward the center thereof.

After the gas has passed the first pair of baffles it must then pass through an entrainment separator 84 constructed of wire mesh or the like. When the gas and lubricant mixture impinges upon the wire mesh the heavier particles of lubricant will cling to the mesh and drain downwardly to the central drain. As the mixture continues through the oil separator it is required to pass through several more pairs of baffles and entrainment separators until it reaches a pocket or open space in the central portion of the oil separator at which time substantially all of the lubricant has been removed from the gas. The lubricant-free gas is then discharged through a line 85 into the check valve 4-0 and line 40 and then into the refrigerating system. The lower portion of the central pocket is provided with an imperforate plate 86 which separates the gas receiving pocket from the lubricant drain 41 to prevent any tendency of the gas to again entrain the lubricant.

The lubricant which has drained to the central portion of the oil separator and is discharged through the drain 41 then is received within the lubrication reservoir 42. Such reservoir preferably has a pair of inspection ports 87 and 88 each of which has a glass plate 89 to permit the level of the lubricant within the reservoir to be observed at all times. The opposite end of the reservoir is provided with a lubricant charging valve 90 to replenish the small amount of lubricant which is lost through entrainment With the gas which is discharged from the oil separator.

As illustrated in FIGS. 1517 the lubricant heat exchanger 45 is located intermediate the side members 11 of the base 10. Such heat exchanger includes a plurality of elongated tubes 93 connected by lubricant headers 94 and 95. Each of the headers 94 and 95 is provided with a series of baffles 96 and most of such baflles are spaced apart a distance slightly greater than the spacing of two of the tubes 93. The lubrication header 94 has an inlet 97 at one end and an outlet 98 at the opposite end. The outermost baffle at each end of the header 94 is spaced from the inlet and outlet respectively a distance slightly greater than the diameter of one of the tubes 93 so that the lubricant passing through the inlet will impinge upon the first baffle and be directed through the first tube where it is discharged into the header 95. The lubricant then passes to the first baffle of the header 95 and is forced back through the second tube 93 into the header 94. The lubricant continues in a serpentine path through the heat exchanger until it passes through the last tube and is discharged through the outlet 98.

In order to effect the transfer of heat from the lubricant a plurality of pipes 99 are disposed within each of the tubes 93 and such pipes pass through the headers 94 and 95 into water headers 100 and 101 mounted on the lubrication headers 94 and 95, respectively. The header 100 is provided with a central bafile 102 dividing such header into two compartments and one of such compartments is provided with a water inlet 103 and the other compartment is provided with a water outlet 104. Cool water is introduced into one compartment of the header 100 where it passes through the pipes 99 connected therewith and is discharged into the header 101. The water thus discharged into the header 101 will flow to the opposite side thereof and thence back through the pipes 99 on the opposite side of the heat exchanger into the second compartment of the header 100 where it will be discharged through the outlet 104. It will be noted that the water will flow in the samedirection as the lubricant in some of the tubes 93 and will flow counter to the flow of the lubricant in other tubes.

In the operation of the device, refrigerant gas which has passed through the refrigerating system flows through the inlet pipe 30 into the suction trap 31 where most of the impurities and foreign matter are filtered out. The refrigerant gas then is discharged from the suction trap through the inlet line 32 into the suction manifold 26 of the rotary sliding vane compressor. The rotor 20 is driven by the motor 54 and such rotor has a plurality of grooves 21 in which the sliding vanes 22 are received. The rotor is rotated at a speed such that the tip speed of the vanes is greater than the velocity of the incoming gas so that the rotor creates a suction to cause the gas to enter the spaces or pockets between two vanes at a point where the volume of such pockets is relatively large. As the rotor continues to rotate the vanes will seal off the pockets and the gas trapped within such pockets will be compressed due to the changing volume caused by the eccentric mounting of the rotor within the compressor housing 14 as well as by the reciprocating movement of the vanes. As soon as the individual pockets are sealed and while they are still relatively large in volume, lubricant is injected through the inlet ports 49. The lubricant inlet ports are distributed throughout the length of the compressor housing so that the lubricant is equally distributed and will not cause a centralized bulk which would cause the vanes to vibrate or chatter and cause excessive wear and resulting noise. The introduction of the lubricant into the pockets assists in the compression of the fluid contained therein as well as in providing a lubricating film to reduce the friction of the moving parts. Also the lubricant absorbs heat from the gas including the heat created by compression and maintains the compressor at a lower operating temperature. During the compressing of the gas the vanes are forced into the grooves 21 and such movement compresses the ga contained therein which had entered through recesses 23 at the time that the pockets were being filled. The compressing of the gas within the grooves forces such gas back through the recesses 23 into the pocket between the vanes and additionally assists in the compressing of such gas in the pockets. When the gas has reached the desired compression ratio, such gas is discharged through the discharge ports 19 into the discharge manifold 35. The discharge ports are arranged in such a manner that they permit the gas within the pockets to be discharged into the discharge manifold 35 at substantially the same pressure even though the ga within the pockets is continuing to be compressed by the movement of the rotor. The gas which is discharged within the discharge manifold passes through the oil lift sleeve 35' and a discharge valve and into the oil separator 39 which separates substantially all of the lubricant from the gas and returns the gas to the refrigerating system while discharging the lubricant into a reservoir. The lubricant in the reservoir is removed by an oil pump which passes such lubricant through the heat exchanger 45 after which the lubricant passes through a filter into a distribution header for injection back into the compressor housing. The lubricant within the compressor housing is in heat exchange relation with the refrigerating gas and absorbs part of the heat therefrom and subsequently the lubricant is passed through the heat exchanger to remove such heat in a repetitive cycle.

It will be obvious to one skilled in the art that various changes may be made in the invention without departing from the spirit and scope thereof and therefore the invention is not limited by that which is illustrated in the drawings and described in the specification, but only as indicated in the accompanying claims.

What is claimed is:

1. In a rotary sliding vane compressor having spaced inlet and discharge ports in a circumferential wall of a cylinder, and a cylindrical rotor eccentrically mounted within said housing and in proximity to said wall at a location between the discharge and inlet ports in the direction of rotor travel, said rotor having a plurality of radial grooves and vanes slideable therein, the improvement comprising inlet ports having an area which varies along the path of travel of the vanes such that initially the rate of increase of the inlet port area varies directly with the volume increase of the corresponding pocket and that during decrease of said port area the rate of decrease is substantially constant.

2. In a rotary sliding vane compressor having spaced suction and discharge ports in a circumferential wall of a cylinder, a cylindrical rotor eccentrically mounted within said cylinder and in proximity to said wall at a location between the suction and discharge ports in the direction of rotor travel, said rotor having a plurality of radial grooves, a vane slideably mounted in each of said grooves for engaging said wall by peripheral force, said vanes forming pockets between the wall and rotor which vary in volume as the rotor rotates, the improvement comprising said ports consisting of slots, said slots extending in a direction around the cylinder and angularly disposed to a circumference, certain of said slots extending around substantially the entire arc of the inlet area, other slots extending lesser and varying distances around the arc, all of said slots terminating in the direction of rotor travel at substantially the same circumferential position.

3. In a rotory sliding vane compressor having spaced suction and discharge ports in a circumferential wall of a cylinder, and a cylindrical rotor eccentrically mounted within said housing and in proximity to said wall at a location between the discharge and suction ports in the direction of rotor travel, said rotor having a plurality of radial grooves and vanes slideable therein, said vanes forming pockets which vary in volume as the rotor rotates, said compressor being so constructed and designed that fluid received in the suction port is compressed to a nominal predetermined volume, the improvement comprising providing a relatively small discharge port area in the cylinder just prior to the position at which the pocket reaches the nominal predetermined volume.

4. In a rotary sliding vane compressor having spaced suction and discharge ports in a circumferential Wall of a cylinder, and a cylindrical rotor eccentrically mounted within said housing and in proximity to said wall at a location between the discharge and suction ports in the direction of rotor travel, said rotor having a plurality of radial grooves and vanes slideable therein, said vanes forming pockets which vary in volume as the rotor rotates, said compressor being so constructed and designed that fluid received in the suction port is compressed to a nominal predetermined volume, the improvement comprising said discharge port having a relatively small initial area followed immediately by an area many times larger for permitting substantially unimpeded discharge of the compressed fluid.

5. In a rotary sliding vane compressor having spaced suction and discharge ports in a circumferential wall of a cylinder, and a cylindrical rotor eccentrically mounted within said housing and in proximity to said wall at a location between the discharge and suction ports in the direction of rotor travel, said rotor having a plurality of radial grooves and vanes slideable therein, said vanes forming pockets which vary in volume as the rotor rotates, said compressor being so constructed and designed that fluid received in the suction port is compressed to a nominal predetermined volume, the improvement comprising said ports consisting of narrow slots extending in a direction around the circumference of the cylinder, said slots having relatively narrow inner edges and having diverging surfaces extending to the outer surface of the cylinder.

6. In a rotary sliding vane compressor having spaced inlet and discharge ports in a circumferential wall of a cylinder, and a cylindrical rotor eccentrically mounted within said housing and in proximity to said wall at a location between the discharge and inlet ports in the direction of rotor travel, said rotor having a plurality of radial grooves and vanes slideable therein, said vanes forming pockets which vary in volume as the rotor rotates, the improvement comprising inlet ports having an area which varies along the path of travel of the vanes such that initially the rate of increase of the inlet port area varies directly with the volume increase of the corresponding pocket and that during decrease of said port area the rate of decrease is substantially constant, said compressor being so constructed and designed that fluid received in the inlet port is compressed to a nominal predetermined volume at the discharge port, and a relatively small discharge port area in the cylinder just prior to the position at which the pocket reaches the nominal predetermined volume.

7. In a rotary compressor comprising a housing having an internal cavity with a cylindrical wall, a cylindrical rotor eccentrically mounted within said housing, said rotor having a plurality of radial grooves, a vane slideably mounted in each of said grooves for engagement with said wall through centrifugal force, said vanes forming pockets which vary in volume as the rotor rotates, said rotor and vanes being of fixed length along the axis of the rotor, the improvement comprising said housing having means whereby its axial length may be adjusted to provide the desired clearance at each end of the housing between the rotor and vanes and the housing, and scalable inspection ports extending through the housing at each end thereof and overlying the ends of the rotor, whereby the clearance may be visually checked and appropriate adjustment made if necessary.

8. In a rotary sliding vane compressor having spaced suction port means communicating with an inlet and discharge port means communicating with an outlet, said means in a circumferential Wall of a cylinder, and a cylindrical rotor eccentrically mounted within said cylinder and habing a seal point at a location between the discharge and suction ports in the direction of rotor travel, said rotor having a plurality of radial grooves and vanes slidable therein, said vanes forming fluid working chambers which vary in volume as the rotor rotates to admit and to compress the fluid within the working chambers, the improvement comprising said discharge port means having an effective area which varies as the vanes move relative thereto, such area being relatively small when the chamber is initially in communication with the outlet, the volume of the chamber then being relatively large, such area increasing as the leading vane of the chamber moves towards the seal point and its volume decreases, the rate of increase of said flow area increasing as the chamber volume decreases such that during the major portion of the discharge the pressure within the chamber remains substantially constant and the fluid is discharged at a velocity substantially the same as the linear velocity of the end edges of the vanes adjacent to the discharge port means.

9. The apparatus of claim 8 in which the nominal discharge velocity through the discharge port means is percent to percent of the average peripheral velocity of the blades.

10. In a rotary sliding vane compressor having spaced suction and discharge port means in a circumferential wall of a cylinder, and a cylindrical rotor eccentrically mounted within said cylinder and in proximity to said Wall at a location between the discharge and suction ports in the direction of rotor travel, said rotor having a plurality of radial grooves and vanes slidable therein, said vanes forming fluid working chambers which vary in volume as the rotor rotates to compress the fluid within the working chambers, the improvement comprising said discharge port means having a plurality of slots spaced from each other in a direction along the length of the rotor and with half of the slots on one side of a centrally located slot sloping away from the other half of slots in the direction of movement of the vanes relative thereto, the slots being of varying lengths but terminating along a common imaginary line adjacent the end of the effective part of the slots.

References Cited by the Examiner UNITED STATES PATENTS 1,087,962 2/1914 Matchette et al. 230-152 1,142,544 6/1915 Vernon et al 230-207 1,210,730 1/1917 Vernon 230-152 1,732,039 10/ 1929 Cuthbert 230-207 2,027,594 1/1936 Huff 230-152 2,094,323 9/1937 Kenny et al 230-152 2,251,784 8/1941 Dick et al 230-152 2,540,714 2/1951 Curtis et al 230-207 2,641,405 6/1953 Le Valley 230-210 2,824,687 2/1958 Osterkamp 230-152 3,059,836 10/1962 Nash et al 230-152 FOREIGN PATENTS 388,990 3/1933 Great Britain. 480,522 2/ 1938 Great Britain.

MARK NEWMAN, Primary Examiner. R. M. VARGO, Assistant Examiner. 

1. IN A ROTARY SLIDING VANE COMPRESSOR HAVING SPACED INLET AND DISCHARGE PORTS IN A CIRCUMFERENTIAL WALL OF A CYLINDER, AND A CYLINDRICAL ROTOR ECCENTRICALLY MOUNTED WITHIN SAID HOUSING AND IN PROXIMITY TO SAID WALL AT A LOCATION BETWEEN THE DISCHARGE AND INLET PORTS IN THE DIRECTION OF ROTOR TRAVEL, SAID ROTOR HAVING A PLURALITY OF RADIAL GROOVES AND VANES SLIDEABLE THEREIN, THE IMPROVEMENT COMPRISING INLET PORTS HAVING AN AREA WHICH VARIES ALONG THE PATH OF TRAVEL OF THE VANES SUCH THAT INITIALLY THE RATE OF INCREASE OF THE INLET PORT AREA VARIES DIRECTLY WITH THE VOLUME INCREASE OF THE CORRESPONDING POCKET AND THAT DURING DECREASE OF SAID PORT AREA THE RATE OF DECREASE IS SUBTANTIALLY CONSTANT. 